1. Field of the Invention
The present invention relates, in general, to rotary compressors and, more particularly, to a variable capacity rotary compressor, which is designed such that a compression operation is executed in either of two compression chambers having different capacities, by an eccentric unit mounted to a rotating shaft.
2. Description of the Related Art
Generally, a compressor is installed in a refrigeration system, such as an air conditioner and a refrigerator, which cools air in a given space using a refrigeration cycle. In the refrigeration system, the compressor compresses a refrigerant which circulates through a refrigeration circuit. A cooling capacity of the refrigeration system is determined according to a compression capacity of the compressor. Thus, when the compressor is designed to vary a compression capacity thereof as desired, the refrigeration system is operated under an optimum condition considering several factors, such as a difference between a practical temperature and a predetermined temperature to allow air in a given space to be efficiently cooled, and to save energy.
A variety of compressors are used in the refrigeration system. The compressors are typically classified into two types, that is, rotary compressors and reciprocating compressors. The present invention relates to the rotary compressor, which will be described as follows.
The conventional rotary compressor includes a hermetic casing, with a stat or and a rotor being installed in the hermetic casing. A rotating shaft penetrates through the rotor. An eccentric cam is integrally provided on an outer surface of the rotating shaft. A roller is provided in a compression chamber to be fitted over the eccentric cam.
The conventional rotary compressor is operated as follows. As the rotating shaft rotates, the eccentric cam and the roller execute eccentric rotation in the compression chamber. A gas refrigerant is drawn into the compression chamber, compressed, and then discharged as the compressed refrigerant to an outside of the hermetic casing.
However, the conventional rotary compressor has a problem in that the conventional rotary compressor has a fixed compression capacity. Therefore, varying the compression capacity, according to a difference between an environmental temperature and a preset reference temperature, is very difficult.
In a detailed description, when the environmental temperature is considerably higher than the preset reference temperature, the compressor must be operated in a large capacity compression mode to rapidly lower the environmental temperature. Meanwhile, when the difference between the environmental temperature and the preset reference temperature is not large, the compressor must be operated in a small capacity compression mode so as to save energy. However, since changing the capacity of the rotary compressor according to the difference between the environmental temperature and the preset reference temperature is very difficult, the conventional rotary compressor does not efficiently cope with a variance in temperature, thus leading to a waste of energy.